The prior art pertinent to the present invention is exemplified by the technique described in the publication of C. V. Thompson et al, "Positome II: A High Efficiency Positron Imaging Device for Dynamic Brain Studies", IEEE Trans. Nucl. Sci. NS.-26:583-589, 1979. In the system described in this publication, the timing pulse in each channel is delayed about 500 ns or more, until the energy of the pulse has been verified, and then it is presented to a coincidence detector. This technique has two disadvantages: Firstly, a precision delay is needed for each channel, and this becomes highly expensive in a positron emission tomograph (PET) scanner with hundreds of channels. Secondly, any instability in the channel delays directly degrades the accuracy with which time coincidence between events in different channels can be determined, and the instability will be proportional to the magnitude of the desired delay.
Further background information pertinent to the present invention is provided in the publication of R. A. Brooks et al, "Design of a High Resolution Positron Emission Tomograph: The Neuro-PET", Journal of Computer Assisted Tomography, 4(1):5-13, February, 1980, incorporated by reference.
The patent literature, for example, De Luca, U.S. Pat. No. 3,935,462; Alvarez et al, U.S. Pat. No. 4,029,963; Giraud et al, U.S. Pat. No. 4,031,392; Brunett et al, U.S. Pat. No. 4,042,811; Cox et al, U.S. Pat. No. 4,044,240; Lyons, U.S. Pat. No. 4,181,939; and Daniels et al, U.S. Pat. No. 4,217,497 show systems including computers interfaced with radiation detectors and nuclear imaging systems, but these do not solve the problems noted above.